1. Field of the Invention
The present invention relates to an improvement in an ignition plug cap for providing electric high-voltage pulses to an ignition plug used in a vehicle and, more particularly, to an ignition plug cap which is capable of providing a constant secure ignition to the ignition plug for a substantially long period.
2. Description of the Prior Art
Heretofore, there has been provided a conventional ignition plug cap applied to an engine, or the like, of a vehicle, a case in point being the one as disclosed in FIG. 5. Here, the ignition plug cap of this type is constructed such that a discharge tube 4 is disposed between a cable terminal 3a of a high-tension cord 3 and a connecting terminal 2, which is detachably coupled with a terminal 1a of an ignition plug 1, wherein these members are all covered with a casing 5 made of an insulation resin coat to be firmly settled therein. However, it is to be noted that there has also been provided an ignition plug cap which has no discharge tube adopted therein.
In a conventional type ignition plug cap without a discharge tube installed therein a rise of temperature due to the heat conducted from the engine is considered. In the discharge-tube-installed type ignition plug cap, however great care should be taken so as not to generate an excessive rise of temperature since the operation of the discharge tube, itself, generates a great amount of heat, especially when driving on a free way or climbing a continuous rising slope for a substantially long period. Such operation deteriorates the functioning of the ignition plug as a whole, so that some kind of protecting method should be taken into consideration in order to protect the ignition plug from this phenomenon.